June 20 Summer begins. Because of the tilt of the Earth's axis, tonight, the Summer Solstice, will be one of the shortest nights of the year, with sunset at around 8:30 p.m. and sunrise the next day around 5:30 a.m. giving 9 hours of darkness and 15 hours of light. The Winter Solstice, in December, is, by contrast, one of the longest nights of the year with around 9 hours of light and 15 hours of darkness.